Bobcat Returns to Southwest Preserves

During a deer survey one winter night in the woods, a high-pitched scream startled Animal Ecologist Dan Thompson of the Forest Preserve District of DuPage County. It was the call of a lovesick Lynx rufus, the reclusive bobcat. Once on the Illinois threatened species list, counts done in the 1990s showed a steady increase in bobcat numbers throughout the state, and the species was subsequently removed from the list. But in the Chicago metro area?!

For years, the district staff heard rumors of bobcat sightings, usually in Waterfall Glen, a 2,474-acre heavily wooded preserve surrounding Argonne National Laboratory. District staff hoped the rumors were true, but they had no proof until 2002, when confirming tracks were finally spotted, first in Waterfall Glen, then in the 1,425-acre Greene Valley Preserve.

Scientists believe that bobcats need about five square miles to roam. Although neither preserve is that large, Waterfall Glen is adjacent to Cook County's Palos preserves, which total about five square miles. The bobcats detected in Greene Valley may be using the DuPage River to access other preserves and rural land. Both Greene Valley and Waterfall Glen have remote wooded areas far away from highways and hiking trails.

Perhaps more important to the bobcats' success in DuPage County are the over-large populations of white-tailed deer. Bobcats prey on young deer and, like coyotes, prey upon deer incapacitated by collisions with automobiles. Bobcats also eat rabbits, birds, and many other species.

Using scent stations, district staff have begun a monitoring program to find out how widespread these animals are in the two preserves. At each station, a swab, dipped in the bottled scent of a female bobcat in heat, is placed on cardboard in remote locations and surrounded with powder to make tracks visible. The scent is a sure draw for roaming males in search of a mate.

By the end of the program this summer, the district hopes to determine bobcat numbers, location, and preferred range, so staff can take any needed steps to protect this important animal.

"The bobcat is a predator that serves a vital role in maintaining the ecological balance and health of a preserve," said Thompson. "Even if they are only surviving in the larger preserves with more secluded areas, it shows we are on the right track. To be able to sustain such a reclusive and conservative animal as the bobcat amongst all the development is amazing." But don't expect to ever see one. That hair-raising scream is the closest the bobcats ever come.

— Elizabeth Riotto